1-Methoxy-1-silacyclohexane: Synthesis, molecular structure and conformational behavior by gas electron diffraction, Raman spectroscopy and quantum chemical calculations

Abstract The synthesis and results of gas electron diffraction (GED), temperature-dependent Raman spectroscopy, along with detailed quantum chemical (QC) study of 1-methoxy-1-silacyclohexane 1 are reported. Within the series of the QC results, DFT(B3LYP, PBE0, M06, M062X), and MP2, the conformational preference predictions are rather contradictive. From the both GED and Raman experimental methods applied, the vapour and liquid phases of 1 were found to exist as a mixture of two conformers, gauche- axial and gauche -equatorial, with almost equal contributions, while the trans -forms are much less stable. In addition, theoretical calculations on the cyclohexane analog, methoxycyclohexane 2 , are performed in order to compare with the conformational properties of 1 . The latter is predicted not to diminish the axial/equatorial ratio, as contrasted to the expectations at switching the point of the substituent attachment from Si to C.